Officials in the Dominican Republic say the presidents of Venezuela, Colombia and Ecuador are expected to attend Friday's summit of the Rio Group in Santo Domingo.

The Dominican Foreign Ministry says the meeting will be a chance for the leaders to discuss their recent differences.

Nicaragua Thursday joined Venezuela and Ecuador in withdrawing its ambassador from Colombia, in response to Colombia's cross-border attack last week on the FARC rebel group. Venezuela and Ecuador have sent troops to their borders with Colombia.

The Organization of American States has approved a resolution calling the attack a violation of Ecuador's sovereignty and international law. U.N. Secretary General Ban Ki-moon welcomed the resolution and said it provides a path to settle the dispute peacefully.

U.S. Secretary of State Condoleezza Rice also called for a diplomatic solution, and warned against allowing the FARC to continue to operate.

Rice is due to visit South America next week, but she is not scheduled to meet with the presidents of Colombia, Ecuador or Venezuela.

The United States considers the FARC a terrorist group.

Colombian officials have defended the incursion, and Colombian President Alvaro Uribe has accused Venezuela of financing and supporting the FARC.